The last two issues of NCE misuse terms describing geotextiles. As the past chairman of the technical committee of the International Geosynthetics Society (IGS) and one of the UK experts to the CEN Technical Committee TC189 Geosynthetics, I would like to explain the basic terminology to you.
Geosynthetic is an allembracing term for a number of different types of materials; geotextiles are permeable sheets which are used with functions of separation, filtration, protection, drainage or reinforcement; and geomembranes are 'impermeable' sheets that function as barriers to the flow of fluids.
The word membrane should not be used in conjunction with geotextile, as in the article on the problems at Ulley Dam (NCE 5 July).
Here, a geotextile is acting as a separator/filter, not as a membrane.
Further in the article the geotextile is described using its trade name Terram, (on three separate occasions, no less).
This is akin to calling a vacuum cleaner a Hoover.
Steve Corbet, technical director, geotechnical, Faber Maunsell, Newlands House, The Newlands, Witham, Essex CM8 2UW